This invention relates to satellites, in particular, using reaction wheel assemblies (RWA) to provide a radiation shield for electronics on a satellite and simplify the integration of RWA""s and electronics in a satellite system.
An RWA comprises a dense, metalic rotor and electronics to change the speed of its rotation. A plurality of RWAs are deployed on a satellite along different rotor axis producing an aggregate angular momentum the direction and magnitude of which is varied, by changing the speed of the RWAs, to change satellite attitude spherically (rotate the satellite).
Typically, the RWAs are located at different locations in the satellite payload area and connected by cables to associate electronics. The electronics needs to be shielded from ambient radiation found in space, and the common technique is to place the electronics in a metal container.
An object of the present invention is provide a modular reaction wheel assembly with the electronics inside and protected from radiation.
According to the invention, the rotors are used to shield the electronics. In particular, the RWAs are arranged around an electronics enclosure on their respective, required off-normal axis orientations to provide full attitude control, the electronics, on circuit boards are located with the enclosure and the RWA rotators, which are thick compared to the housing, provide a barrier between the circuit boards and radiation outside the enclosure. Connectors for the electronics are located on one surface between the RWAs and provide a barrier for one end of the circuit boards. The circuit boards are oriented inside the enclosure so that RWAs shield the surface (maximum exposure area of the electronics) of the circuits boards.
A feature of the present invention is that the RWA assembly can be installed as a singe unit on a satellite reducing integration costs. Another feature is that the total weight of RWA package (electronics and reaction wheels) is reduced compared to traditional approaches where each reaction wheel is separately mounted from the electronics. The invention takes advantage of the radiation shielding qualities of the rotors.
Other objects, benefits and features of the invention will apparent to one of ordinary skill in the art from the drawing and following description.